<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

<script type="text/javascript">
    let promise1 = new Promise((resolve, reject) => {
        resolve('成功的结果');
        //reject('失败的结果');
    }).then((value) => {
        console.log("成功时的回调1", value);
        return a;
    }).catch((error) => {
        console.log("catch1", error);
        return 'catch1 success';
    }).then((value) => {
        console.log("成功时的回调2", value);
        return b;
    }).catch((error) => {
        console.log("catch2", error);
    }).then((value) => {
        console.log("成功时的回调3", value);
    }).catch((error) => {
        console.log("catch3", error);
    })
</script>
</body>
</html>